1. Field of the Invention
The present invention relates to a container for a motor controller of a heat-dissipating device, and in particular to a motor controller and a container for a DC brushless motor in a heat-dissipating device.
2. Description of the Related Art
DC brushless motors are used in many electronic devices, such as heat-dissipating fans. FIG. 1A shows a conventional fan using a DC brushless motor. In FIG. 1A, the fan includes a frame 11, a printed circuit board 12 (PCB), a stator 13, and a rotor 14. When assembling the fan, the PCB 12, stator 13 and rotor 14 are sequentially assembled to a sleeve 111 on a base portion of the frame 11.
Unlike a conventional DC motor, a brushless DC motor includes a Hall sensor to detect the phase change of magnetic field and a driving circuit to convert current direction in the stator winding, rather than the brushes used in the conventional DC motor. The converted current in the stator winding induces a magnetic field to drive the rotor. The Hall sensor in the conventional DC brushless motor is generally disposed on a PCB. In FIG. 1A, the pins of the Hall sensor 15 are surface-mounted on the relative contacts on the bottom surface 121 of the PCB 12, and the Hall sensor 15 is then bent upward, extending into the stator 13.
FIG. 1B shows another structure to fix a Hall sensor on a PCB of the conventional DC brushless motor. In FIG. 1B, a plurality of holes 16 are formed on the PCB 12. The pins 151 of the Hall sensor 12 pass through the holes 15 and are soldered to the bottom surface of the PCB 12.
The circuit of the above conventional mounting methods for Hall sensors is, however, complicated, which reduces available layout area on the PCB and increases fabricating cost. The complicated layout on the PCB also increases impedance and causes considerable power loss. Moreover, since the Hall sensors are not consistently bent to predetermined angles during fabrication, their position corresponding to the position of the magnetic poles will be easily displaced resulting from externally careless collision.
Hence, there is a need for a better DC brushless motor with lower cost, precise angling of a Hall sensor and precise speed control.